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The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
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These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Every ordered field is an ordered ring, and its order is the one its positive cone induces
Statement
Let be an ordered field with positive cone (Ordered field), and let be the relation or that Ordered field defines from . Then:
- with the operations of Field is a commutative ring (Every field is a commutative ring with ; it is an integral domain, and it is a commutative division ring), and is a cone in the sense of The order presentation and the positive-cone presentation of an ordered ring determine each other: satisfies trichotomy and closure, and recovers the order;
- is a total order making an ordered ring (Ordered ring: a ring with a total order compatible with addition and with positives closed under multiplication), whose positive cone is exactly ;
- , that is .
So an ordered field is an ordered ring, and its order and its positive cone determine each other exactly as they do in any ordered ring.
Facts & Assumptions
Given: An ordered field with positive cone , and defined from by or (Ordered field).
Axiom (O1): for each exactly one of , , holds (Ordered field).
Axiom (O2): if then and (Ordered field).
The order of an ordered field is defined by , and means or (Ordered field).
Every field is a commutative ring with (Every field is a commutative ring with ; it is an integral domain, and it is a commutative division ring, Field).
In a ring, a subset satisfying trichotomy and closure under addition and multiplication is a cone, and the relation it induces is a total order making the ring an ordered ring whose positive cone is that subset (The order presentation and the positive-cone presentation of an ordered ring determine each other: satisfies trichotomy and closure, and recovers the order, Ordered ring: a ring with a total order compatible with addition and with positives closed under multiplication).
In an ordered field, implies , that is (Squares of nonzero elements are positive).
Proof
is a commutative ring under its own addition and multiplication, with the same and .
is a cone in the ring : trichotomy is axiom (O1) verbatim, and closure under addition and under multiplication is axiom (O2) verbatim. This proves claim 1.
By [L2] applied to the ring and the cone , the relation or is a total order making an ordered ring, and its positive cone is .
That relation is the order of the ordered field: [A3] defines as and as or , which is the definition of word for word. So and are the same relation, and claim 2 follows.
Claim 3: by [L1], so by [L3]; and because is the multiplicative identity. Hence , that is .
Remarks
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This is one of the four bridges the page carries. The published Ordered field and the Ordered ring: a ring with a total order compatible with addition and with positives closed under multiplication of this page are two presentations of compatible orders, and without this item a later result about ordered rings could not be applied to or without redoing the translation each time.
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The converse is false as stated, and no converse is claimed. is an ordered ring and is not a field at all, as the companion page records. What is true, and is claim 2, is that on a field the two presentations of an order agree.
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Where the strict form of (OR2) is used. Axiom (O2) of Ordered field is already strict, so claim 1 is a verbatim match with the cone conditions of The order presentation and the positive-cone presentation of an ordered ring determine each other: satisfies trichotomy and closure, and recovers the order and no strengthening is needed; that is exactly why Ordered ring: a ring with a total order compatible with addition and with positives closed under multiplication states its multiplicative axiom in the strict form.
Depends on
- Ordered field
- Ordered ring: a ring with a total order compatible with addition and with positives closed under multiplication
- The order presentation and the positive-cone presentation of an ordered ring determine each other: $P = \{\, x : 0 < x \,\}$ satisfies trichotomy and closure, and $a < b :\iff b - a \in P$ recovers the order
- Every field is a commutative ring with $1 \ne 0$; it is an integral domain, and it is a commutative division ring
- Field
- Squares of nonzero elements are positive
Used by
Dependency tree · next 3 levels
Direct dependencies and their dependencies through the next three levels: 42 results over 13 levels. An arrow runs from a result to what uses it, and this result sits at the bottom with a heavier outline. Click the chart to enlarge it.
Sources
- Ordered field (Wikipedia) (standard reference, not scraped)
- Ordered ring (Wikipedia) (standard reference, not scraped)
- Field (mathematics) (Wikipedia) (standard reference, not scraped)